snd_ctl_add_slave — Add a virtual slave control
int snd_ctl_add_slave ( | struct snd_kcontrol * master, |
struct snd_kcontrol * slave); |
Add a virtual slave control to the given master element created via
snd_ctl_create_virtual_master beforehand.
Returns zero if successful or a negative error code.
All slaves must be the same type (returning the same information via info callback). The fucntion doesn't check it, so it's your responsibility.
Also, some additional limitations: at most two channels, logarithmic volume control (dB level) thus no linear volume, master can only attenuate the volume without gain